Lower screen grate apparatus for rock crusher



Sept. 29, 1964 A. B. HANSE ETAL 3,150,837

LOWER SCREEN GRATE APPARATUS FOR ROCK CRUSHER Filed June 18, 1962 IN V EN TORS.

United States Patent 3,159,837 LGWER SCREEN GRATE APPARATUS FOR RQ'BCK RUSHER Albert E. Hanse and Leonard N. Kint, Cedar Rapids,

Iowa, assignors to Pettihone Muliiken Corporation, a

corporation of Delaware Filed June 18, E62, Ser. No. 203,066 3 Claims. (Cl. 241-189) The present invention relates to improvements in a rock crusher. While the present invention can be employed in other types of rock crushcrs, it was devised for use in a crusher of the type in which an impeller rotating about a generally horizontal axis is employed. The: impeller has a plurality of hammers thereon. The rock is deposited on the impeller. Some of the rock is broken by reason of impacts between the moving hammers and the rock and the impeller throws the rock upwardly and to one side. Inteiposed in the path of movement of the rock from the impeller is a screen grate. Small pieces of rock may pass through the grate and out of the crusher. Larger pieces of rock will fracture by impact with the grate.

Occasionally there will be rock which will not be broken either by impact with the hammers or by impact against the grate. If a fixed grate is employed, as is the case with numerous crushers of this type, the grate or other portions of the crusher may be broken or damaged when a rock which will not break becomes jammed between the grate and rotor. To avoid this some crushers have positioned the grate away from the path of movement of the hammers of the rotor a distance sufficient to permit unbroken large rocks to pass therebetween and out of the machine. However, providing such a gap between the two creates the possibility that some rock which would be fractured by impact against the grate will pass through the gap and thus not be broken.

The present invention relates to a mounting structure for a supplemental grate to be positioned to close this gap. Thus, rock which is thrown by the impeller toward the gap between the rotor and the primary screen grate normally will impact against the supplemental grate, hereinafter called the lower screen grate, so that it will be broken in the usual manner. In doing so there again is the possibility of unbroken rock being wedged between the lower screen grate and the moving hammers with resulting damage to the machine. Our invention incorporates a novel mounting structure for the lower screen grate so that should an unbroken rock become so wedged, an inexpensive, easily replaceable, part will be fractured thus saving damage to other parts of the machine.

A further feature of our invention is that provision is made for alternative positioning of the lower screen grate with respect to the path of movement of the hammers. Thus the user can change the maximum size of rock that normally will exit from the machine without rupturing the break-away part of the mounting of the lower screen grate.

The structure of our invention provides a relatively rigid mounting of the lower screen grate. At the same time a slight amount of movement is permitted so that some rocks of borderline size will pass through the crusher without rupturing the break-away portion of the lower screen grate mounting.

An important feature of our invention is that the breakaway portion of the mounting is stressed, and ruptures, in tension. This prevents damage to adjacent parts when the break occurs. In contradistinction, a break-away part that is stressed, and ruptures, in shear usually will score and wear related parts upon the occurrence of each break. Obviously this is damaging to a machine. Furthermore, the related parts may become so damaged that replacement of the break-away part is made difficult if not im- 3,159,837 Patented Sept. 29, 1964 possible. In a shear type device, the ends of the breakaway part sometimes are so deformed that it becomes difficult to remove the broken pieces from the apparatus so that they can be replaced by a new part.

Further objects and advantages will be apparent from the following description taken in conjunction with the drawings in which:

FIGURE 1 is a partial plan view, in section, of a portion of a rock crusher embodying our invention;

FIGURE 2 is a vertical sectional elevation at line 2-2 of FIGURE 1; and

FIGURE 3 is a view taken at line 33 of FIGURE 2 with a portion broken away.

Although the following disclosure offered for public dissemination is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. The claims at the end hereof are intended as the chief aid toward this purpose; as it is these that meet the requirement of pointing out the parts, improvements, or combinations in which the inventive concepts are found.

The rock crusher comprises a rotor or impeller generally 16 which is journaled in the frame of the crusher for rotation about a generally horizontal axis. The frame of the crusher defines an enclosure about the rotor. The enclosure includes a pair of side walls 11 and a back wall 12. A fixed grate, the bottom of which is seen at 13 is secured between side walls 11. A power means, not shown, is connected to rotor it) to rotate it in the direction indicated by arrow 14. A plurality of hammers 15 are releasably afiixed to and form a part of rotor 10. The stone to be crushed is deposited upon an upper part of rotor 10.

With the rotation of the rotor the majority of stone is thrown upward and to the right to impinge against fixed grate 13. The majority of the rock will be broken either by impacts with hammers 15 or by being thrown against fixed grate 13 and impacting thereagainst. However, some of the rock will pass between fixed grate 13 and hammers 15. As previously described, the bottom of the fixed grate is positioned a distance from the path of movement of the hammers such that the largest rocks, if unbroken, will pass therebetween. Usually, this spacing is greater than that illustrated in FIGURE 2, since fixed grate 13 is here illustrated merely to demonstrate the type of crusher with which the present invention is employed and not to show the exact spacing of the grate and rotor.

A lower screen grate generally 17 is positioned to intercept and break the rock which passes in the gap between the fixed grate and rotor. Screen grate 17 is closer to the path of movement of hammers 15 than is the fixed grate 13. The lower screen grate 17 comprises a plurality of generally vertical bars 18 joined by a top cross piece 19 and a bottom cross piece 20. A bottom nose 21 fits over and projects from bottom cross piece 2%. Nose 21 has a plurality of fingers 22 that extend between bars 18. Bolts 23 extend through fingers 22 and bottom cross piece 20 to afiix the two together.

Supports 25 project from each end of the lower screen grate 17 and are held in ways 26 of blocks 27. Blocks 27 are suitably secured to side walls ll. It will be noted that the bottoms of ways 26 slope upwardly as they progress away from rotor 10. At the bottom of grate 17 slots 28 are cut at each end to define pins 2?. Positioning bars 30 have a hooked finger 31 at one end thereof. Finger 31 projects into slot 28 and hooks about pins 29. Bars 30 extend through openings 32 in rear wall 12. A cover 33 is received about bars 30 to close opening 32.

The other end of each of bars 36 has a. plate 35 secured thereto. At each side is a support 36 having an opening 37 through which the bar 343 projects. Support 36 includes angle braces Support 36 is affixed to a mounting member 39 which in turn is secured to wall 11. A tension bolt 41 passes through openings in plate 35 and support 36. Plate 35 and support 36 are held against separation as by means of jam nuts 42 on bolt 41 at opposite sides of those two members. Tension bolt 41 may be partially cut as indicated at 43 so as to break when a predetermined tension is put thereon. An adjustable stop is formed by means of bolt 45 hearing against block 46 on support 36. Bolt 45 is threaded into plate 35 and is held in place by a iam nut 47.

Means are provided to permit grate 17 to be adjusted from one position to the other with respect to rotor 10. One adjustment is that provided by bolt 45 and the position of nuts 42 on bolt 41. A second is provided by stops in ways 25. To this end a circular plate is received in a circular opening in wall 11. Secured to plate 50 is a spacer block 51. When the grate is in the high postion, as illustrated in FIGURES 1 and 2, disk 50 is inserted so that spacer block 51 is in way 26 thereby holding supports upwardly from the bottom of the way. Cap screws 52 and washers 53 prevent plate 59 from coming out of the opening in side plate 11.

Should it be desired to lower grate 17, cap screws 52 are removed so that plate 59 and spacer block 51 may be removed. Plate 50 is turned around so that spacer block 51 now is on the outside of side wal 11. The plate then is reinserted in the opening in wall 11 and cap screws and the Washers replaced. Vs/ith spacer block 51 out of the way, supports 25 may descend to the lower end of way 26 in which position they are closer to rotor 10.

With the lower grate 17 in the raised or lowered position, as desired, nuts 42 on tension bolts 41 are adjusted to a position at which the lower end of grate 17 is the desired distance from rotor 10. Bolt 45 is tightened against block 46 to urge plate away from support 36. Arms 39 now are in a relatively fixed position being urged in one direction by bolt 45 and being retained from further outward movement by tension bolt 41. Being so fixed arms 30 will not rattle or chatter.

Should a rock larger than the space between hammers 15 and grate 17 become lodged therebetween and the rock not be fractured by contact with these parts, the rock obviously will apply an outward pressure (to the right in FIGURE 2) on grate 17. A limited amount of movement of grate 17 may occur by reason of the positioning of supports 25 in ways 26. That is, to a limited extent supports 25 can ride up on ways 26 to permit a rock to enter and perhaps pass through without damaging the parts. However, if this movement is insufiicient to permit the rock to be ejected, and the rock failed to break, grate 17 will be pushed to the right in FIGURE 2. Tension will be applied to bolt 41. Bolt 41 is designed to fracture before suflicient pressure is applied to damage any of the remaining parts of the machine.

Since the majority of rock breaking is occasioned by initial impacts with hammers 15 and with the rocks being thrown by impeller 10 against fixed grate 13 the machine may be continued in operation even though bolt 41 has broken and grate 17 is no longer of any great effectiveness. However, in the majority of instances the operator will desire to stop the machine and replace the broken bolt 41 with a new bolt when this occurs. With grate 17 inoperative, not all of the rock will be broken to the desired size.

The term rock as used herein is employed to not only apply to natural stone, but also to such other materials of similar characteristics which one might wish to crush in a machine of the general type described. An example of such other material would be slag.

We claim:

1. In an apparatus for crushing rock or the like having a frame defining walls, a rotor and a screen grate, the improvement comprising: said grate having projections at each end adjacent the top thereof; a pair of ways secured to the frame and receiving said projections, said ways being downwardly inclined in a direction toward the rotor, said ways supporting said screen grate and permitting it to pivot about a generally horizontal axis; and means connected to the screen grate and frame to hold the other side thereof against pivotal movement away from the rotor and including a rupturable member which is tensioned by a force on the screen grate tending to move the other side away from the rotor, said member being designed to rupture before said force becomes sufficient to break other portions of the screen grate and means.

2. An apparatus as set forth in claim 1, including a removable spacer block in the lower end of each tray, whereby with said spacer block in the way the projection is higher and farther away from the rotor than it is when the spacer block is removed.

3. An apparatus as set forth in claim 2, including a removable insert in the walls opposite the lower end of each way, each spacer block being afiixed to a side of an insert respectively, said inserts being regular in crosssectional configuration whereby they may be inserted with the spacer blocks inwardly or outwardly, and means releasably holding the inserts in the walls,

4. In an apparatus for crushing rock or the like having a frame forming an enclosure with a rotor rotating about a generally horizontal axis in a direction to throw rock in the general direction of a first screen grate spaced from the rotor a distance sufiicient to permit some rock to pass therebetween, the improvement comprising: a second screen grate positioned to intercept rock passing between the grate and the rotor, said grate having projections at each end adjacent the top thereof; a pair of ways secured to the frame and receiving said projections, said ways being downwardly inclined in a direction toward the rotor, said ways supporting said second screen grate and permitting it to pivot about a generally horizontal axis; an arm pivotably connected to said second screen grate adjacent the bottom thereof and extending rearwardly of said grate; a tension device connecting said arm to said frame in a manner such that a force applied to the bottom of the second grate in a direction to urge the bottom away from the rotor will tension said device, said device being designed to rupture under approximately a predetermined tension; and means to prevent said second grate from moving towards said rotor.

5. In an apparatus for crushing rock or the like having a frame forming an enclosure with a rotor rotating about a generally horizontal axis in a direction to throw rock in the general direction of a first screen grate spaced from the rotor a distance sufficient to permit some rock to pass therebetween, the improvement comprising: a second screen grate positioned to intercept rock passing between the grate and the rotor, said grate having projections at each end adjacent the top thereof and a generally horizontal pin on the back side thereof adjacent the bottom; a pair of ways secured to the frame and receiving said projections, said ways being downwardly inclined in a direction toward the rotor, said ways supporting said second screen grate and peimitting it to pivot about a generally horizontal axis; an arm having a hooked finger at one end extending about the back, top and front of said pin, said arm extending rearward from said second grate and through said enclosure; a plate secured to said arm rearwardly of said enclosure; an abutment on said frame between said plate and said finger; a tension bolt connecting said abutment and said plate; and a stop bolt threaded into said plate and extending to and in contact with said abutment.

6. A crusher for rock or the like including a frame, a rotor carried by the frame and rotatable about a generally horizontal axis and including hammer means for striking rock entering the crusher, and an impact unit carried by said frame in the path of rock struck by said hammer means, said impact members being steeply positioned with its upper end more remote from the rotor than its lower end and more remote from the rotor than a vertical plane through the impact surface of its lower portion, pivotable means normally holding the lower portion of said impact unit at a predetermined spacing from the rotor while leaving it free to move vertically, said means being designed to give way if a relatively unbreakable object should be wedged between the rotor and the impact unit, said crusher being characterized by having means iloatingly supporting the upper end of said impact unit in a manner biasing said impact unit by gravity toward a normal operating position but readily yieldable from said position in a direction away from the rotor when struck by a relatively unbreakable object.

7. A crusher for rock or the like including a frame, a rotor carried by the frame and rotatable about a generally horizontal axis and including hammer means for striking rock entering the crusher, and an impact unit carried by said frame in the path of rock struck by said hammer means, said impact member being steeply positioned with its upper end more remote from the rotor than its lower end and more remote from the rotor than a vertical plane through the impact surface of its lower portion, pivotable means normally holding the lower portion of said impact unit at a predetermined spacing from the rotor while leaving it free to move vertically, said means being designed to give way if a relatively unbreakable object should be wedged between the rotor and the impact unit, said crusher being characterized by having means floatingly supporting the upper end of said impact unit in a manner biasing said impact unit by gravity toward a normal operating position but readily yieldable from said position in a direction away from the rotor when struck by a relatively unbreakable object, said last named means including a pair of ways downwardly inclined in a direction toward the rotor and extending in a direction generally radial with respect to the axis of the rotor, and support means for the impact unit movable along said ways to be readily movable upwardly thereon when a relatively unbreakable object is wedged between the rotor and the impact unit.

8. A crusher for rock or the like including a frame, a rotor carried by the frame and rotatable about a generally horizontal axis and including hammer means for striking rock entering the crusher, and an. impact unit carried by said frame in the path of rock struck by said hammer means, said impact unit being supported in part at least by floating support means including a pair of ways carried by the frame and sloping downwardly toward the rotor generally in a radial direction with respect to the rotor axis, and means movable along said ways for supporting said impact unit in a manner biasing the impact unit toward the rotor while allowing it to move freely away from the rotor when a relatively unbreakable object is wedged between the rotor and the impact unit.

References Cited in the file of this patent UNITED STATES PATENTS 2,618,438 Chrystal Nov. 18, 1952 2,767,928 Hanse et al. Oct. 23, 1956 2,862,669 Rollins Dec. 2, 1958 

8. A CRUSHER FOR ROCK OR THE LIKE INCLUDING A FRAME, A ROTOR CARRIED BY THE FRAME AND ROTATABLE ABOUT A GENERALLY HORIZONTAL AXIS AND INCLUDING HAMMER MEANS FOR STRIKING ROCK ENTERING THE CRUSHER, AND AN IMPACT UNIT CARRIED BY SAID FRAME IN THE PATH OF ROCK STRUCK BY SAID HAMMER MEANS, SAID IMPACT UNIT BEING SUPPORTED IN PART AT LEAST BY FLOATING SUPPORT MEANS INCLUDING A PAIR OF WAYS CARRIED BY THE FRAME AND SLOPING DOWNWARDLY TOWARD THE ROTOR GENERALLY IN A RADIAL DIRECTION WITH RESPECT TO THE ROTOR AXIS, AND MEANS MOVABLE ALONG SAID WAYS FOR SUPPORTING SAID IMPACT UNIT IN A MANNER BIASING THE IMPACT UNIT TOWARD THE ROTOR WHILE ALLOWING IT TO MOVE FREELY AWAY FROM THE ROTOR WHEN A RELATIVELY UNBREAKABLE OBJECT IS WEDGED BETWEEN THE ROTOR AND THE IMPACT UNIT. 